Amazon's bestseller lists include products almost no other retailer sells. Surprise hits such as dog seat belts are evidence that in the internet age, buying staff don't decide what sells, customers do. Retailers, therefore, need to recognise that giving customers the power to choose what is right for them is critical in discovering future hits. If a retailer doesn’t offer what a customer is looking for, the ease of shopping around online means that the customer is likely to take their business elsewhere.